The present invention relates to a radio frequency identification (RFID) device using a single antenna for multiple resonant frequency ranges. RFID is a technology that incorporates the use of electromagnetic or electrostatic coupling in the radio frequency (RF) portion of the electromagnetic spectrum to uniquely identify and communicate with a device attached to an object, animal, or person. With RFID, the electromagnetic or electrostatic coupling in the RF portion of the electromagnetic spectrum is used to transmit signals.
A typical RFID system includes a reader (interrogator) and a plurality of tags. A reader includes an antenna and a transceiver, and transmits a radio frequency signal to a tag to initiate a response from the tag. The tag (RFID device) contains an antenna, circuitry, and information to be transmitted to the reader. The tag antenna enables the circuitry to transmit its information to the interrogator, which converts the radio waves reflected back from the RFID device into digital information that can then be passed on to computers that can analyze the data.
Conventional RFID devices are typically designed for use in a particular frequency range, and according to a single communication protocol. Modifying the RFID devices to operate in additional frequency ranges, and with additional communication protocols, requires significant and costly modifications.
In current EPCglobal® passive device architecture, the amount of time that an RFID device can receive and transmit data per session is limited, due to the minimal amount of charge that the RFID passive device can store. In addition, the communication link between interrogator and RFID device in current RFID systems is limited in range due to constraint distance parameters of powering the RFID device.